The Government says it is "making every effort" to prevent class sizes increasing, despite an "unprecedented increase in pupil numbers".
A Department for Education spokesperson said £5 billion had been given to councils to spend on new school places over the course of this Parliament - prompting the creation of 260,000 new school places in shortage areas, "with more planned".
"We have also confirmed a further £2.35 billion to support councils to create the places needed by September 2017, and are allowing good schools to expand without the restrictions and bureaucracy they faced in the past."
The spokesperson added that children are only allowed to join classes of 30 or more in "exceptional cases", adding that the proportion of primary pupils in classes over 36 in size had fallen since the coalition took power.
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